Support for filaments in thermionic valves and other tubes



March 1 1 1924." 1,486,432

B. HODGSON ET AL SUPPORT FOR FILAMENTS IN THERMIONICVALVES AND OTHER TUBES .Fii'ed Aug. 22. 1921 in the tubular part BENJAMIN SUPPORT HOZJGSOH, 3F PORTSMOUTH, AND

FIELDS, LONDON, ENGLAND.

STANLEY ROBERT MULLARD, OF SOUTH- Application filed August 22, 1921. Serial No. 494,275.

To all whom it may concern:

Be it known that We, BENJAMIN Hono- SON and STANLEY ROBERT MULLARD, residents of H. M. Signal School, Royal Naval Barracks, Portsmouth, in the county of Hants, England, and 71 Standen Road, Southfields, London, England, respectively, both subjects of the King of (ireat Britain, have invented certain new and useful Improvements in and Relat'in to Supports for Filaments in Thermionic alves and Other Iubes (for which we have filed an application in England December 24th, 1920), of which the following is a specification.

This invention relates to supports for filaments in thermionic valves and other tubes, such as vacuum tubescontaining fine or delicate filaments for emitting light, and more particularly for tension spring supports for such filaments.

According to this invention, the filament tension spring is enclosed in a tubular part of the valve or tube envelope which extends some distance from the envelope so that the spring is arranged a convenient or suitable distance from the main envelope of the valve Or tube. By this means the envelope of the valve or tube may be baked Without a corresponding baking of the filament ten sion spring.

The invention is illustrated in the figure of the accompanying drawing. A tubular extension A of the envelope B is made sufliciently long to project outside the oven used in baking the envelope during evacuation. The filament tension spring is enclosed A and is arranged as far as ispossible from the main envelope B. A guide piece C which may be a tube fixed rigidly to the envelope B prevents lateral motion of the part" at which the filament i3 is attached to the spring D and supporting wire E. This method of mounting the filament tension spring enables the valve or' e or tube.

tube to be baked without changing the initial tension applied to the filament in the assembling of the valve. The guide piece maintains the filament at a. correct relative distance from the other parts of the valve The increased distance between the spring and the filament avoids loss of elasticity due to heat being conveyed to the spring from the hot Working parts during the normal Working of the valve. The method of mounting is applicable to vacuum vessels containing any arrangement of filaments and any number of electrodes.

Having thus described our invention What we claim as new and desire to secure by Letters Patent is 1. In combination, a vacuum tube envelope, a filament, a spring fastenedto said filament, and means extending from said envelope whereby said spring maintains a uniform tension on said filament during abnormal heating of said envelope.

2. In combination, a vacuum tube envelope, a filament, a tubular portion extending from said envelope, and a spring fastened to said filamentand disposed within the tubular extension, whereby said spring maintains a uniform tension on said filament during abnormal heating of said envelope.

3. In combination,a vacuum tube envelope, a filament, a filament supporting wire fastened to saidfilament, a spring fastened to said supporting wire, a guide piece attached to the envelope for guiding the supporting wire, said guide piece separating the spring from the vacuum tube envelope, and a tubular extension on the vacuum tube envelope, said extension enclosing the wire and the spring whereby said spring maintains a uniform tension on said filament during abnormal heating of said envelope.

BENJAMIN HODGSON. STANLEY ROBERT MULLARD.. 

